The invention relates to a process for producing a supporting shell for a seat and a process for producing a cushion support for a seat.
Seats known in the prior art are substantially composed of a supporting structure for the seating surface and the backrest that are each provided with cushion supports. Seats such as office chairs or seats in motor vehicles exhibit adjustability so that the seat can adapt to the respective seat user. Thus, for example, the inclination of the seating surface and/or the backrest can be adjusted. Additional adjusting devices disposed particularly in the backrest, for example, a backrest width-adjuster, a lumbar support, a horizontally extending bending axis, etc. are known in the prior art. These known adjusting devices are intended to enable the best possible adaptation of the seat to the respective seat user.
In principle, maximum seating comfort is achieved when the contour of the seating surface and/or the backrest of the seat agree extensively with the physiological form of the seat user.
However, the contour of seats known in the prior art corresponds only to a limited extent to the body form of the different possible seat users while allowing for the freedom of movement that is desired (and required for performing the task of driving, in the case of a seat for a motor vehicle). In order to still achieve good contact comfort, the region of the seating surface and/or backrest of seats known in the prior art are provided with cushion supports that have relatively thick foam in order to compensate firstly for the incongruity between the contour of the seating surface and/or backrest and secondly the body of the seat user. These cushion supports require relatively large installation space due to the thickness of the cushion foam.
It is an object of the present invention to specify a process, which forms the prerequisite of being able to produce a seat that provides a high degree of seating comfort and requires less installation space.
This and other objects are achieved according to the invention by providing the supporting substructure of the seat with a shape that most closely approximates the body form of the plurality of possible seat users so that the supporting substructure, with its good fit, necessitates only a relatively thin cushion support in order to achieve good seating comfort. This supporting substructure is referred to hereinafter as a “supporting shell” in the context of the present invention.
According to an aspect of the invention, the cushion support of the seat is provided with a shape that most closely approximates the body form of the plurality of possible seat users so that the cushion support can be designed so as to be relatively thin due to its good fit. In doing this, very good seating comfort is achieved. Here, the supporting substructure of the seat can be approximately planar or it can have a three-dimensional contour.
In the process of the invention, a measuring mat is placed on a seat frame comprising planar and non-cushioned bearing surfaces for the seating surface and/or the backrest. The measuring mat is flexible in space and it has less inherent rigidity so that it can adapt to the body form of a test subject without any significant resistance under the action of the body weight (particularly on the seating surface) and the contact pressure (particularly on the backrest) of the test subject. A measuring mat of similar type is disclosed in DE 196 01 972 C2. The measuring mat disclosed therein is in the form of a hollow body which has flexible partition walls and the interior of which comprises, for example, a plurality of small spherical solid bodies that can be displaced relative to each other with little effort. The solid bodies can be fixed in place by the application of negative pressure so that a surface contour of the measuring mat produced by the test subject is “frozen.” After the test subject has left the measuring mat, the surface contour produced by the test subject is retained due to the negative pressure applied. According to the invention, the surface contour produced on the measuring mat is detected, for example, by use of a multi-coordinate measuring device. The thus scanned data of the surface contour of the measuring mat are stored in a computer unit. This completes an in-seat measurement carried out with a test subject.
The seat frame for receiving the measuring mat can comprise a device for altering the angle between the backrest and the seating surface. Alternatively, the as-designed position of the seat can be reproduced by way of a seat frame, in which there exists a fixed angle between the backrest and the seating surface.
In the in-seat measurement, as mentioned above, the measuring mat is deformed as a result of the body weight and the static contact pressure of the test subject in the mere action of the test subject sitting down on the measuring mat. Depending on the type of seat, the in-seat measurement can be supplemented by a “dynamic component” in that the test subject performs the movements that are typical of a seat user and are reflective of the freedom of movement required by the seat user. In the case of a seat for a motor vehicle, these movements are the ones required to be carried out by a vehicle driver to perform the task of driving, for example, steering, accelerating, braking, etc.
The in-seat measurements are repeated with a plurality of test subjects of different heights, different weights and different physiques. As far as possible, the in-seat measurements cover the entire range extending from the so-called “5% woman” to the so-called “95% man.” The surface contour of the measuring mat produced by every test subject is measured and stored in the computer unit.
On the conclusion of the in-seat measurements, the “measured surface contours” of all test subjects are superimposed onto each other and an “average surface contour” is computed.
The process of the invention differs fundamentally from the process disclosed in DE 196 01 972 C2. DE 196 01 972 C2 relates to a process for detecting the surface contour of an elastic seat cushion, said surface contour resulting under the action of a person seated on the cushion. In order to be able to detect the surface contour of the cushion, a measuring mat of much less layer thickness is used, which measuring mat practically does not alter the seating behavior and the contour of which reflects the surface contour of the elastically deformed cushion located thereunder.
By contrast, according to the invention, a set of surface contours is produced on a non-cushioned, planar seat frame by means of in-seat measurements carried out with different test subjects by the use of a measuring mat, the thickness of which is sufficient for the measuring mat to replace a cushion and to adapt completely to the contour of the seat user. The surface contours are superimposed onto each other to form an average surface contour that is used as a basis for designing a supporting structure that is intended for a seat and that includes the thinnest possible cushioning pad or as a basis for designing an accurately fitting cushion support.
The superimposition of the measured surface contours, referred to hereinafter as “scans,” onto each other is substantially carried out in three steps.
In a first step, a section of the contact surface of the seat user with the seat, in which the scans are to be aligned to each other, is determined. Basically, any section of the contact surface is suitable for this purpose. However, those sections of the contact surface are particularly suitable, in which the geometric shape of the scans and the space coordinates of the scans deviate from each other to the least possible extent. As studies have shown, there are relatively large geometric similarities and relatively few deviations in the space coordinates in the region of the depression created by the buttocks (pelvic region) of the test subjects and the lower back section (lumbar region). The alignment of the scans to each other on the selected section means an alignment of the scans according to the conformities in the geometry of this selected section (“best-fit” process) and thus a displacement of the scans from their actual measured position in space into a common plane.
In the example of the region of the depression created by the buttocks of the test subject, this procedure means that the surface contour created by the “5%-woman” is displaced in the direction of the vertical axis of the seat to the “level” of the “95%-man” (or vice-versa) until both depressions created by the buttocks are located in one plane. Thus surface contours are offset exclusively based on their shapes, irrespective of their measured location in space, by means of an alignment of all scans according to this “best-fit” process, the remaining sections (e.g. the shoulder region) also being displaced together with the selected section (e.g. depression created by the buttocks).
In a second step, the thus aligned scans are averaged arithmetically. The “average surface contour” of all measured scans is computed by use of an averaging function known in CAD programs (for example, CATIA program). The basis for the averaging process is formed by the respective surface contours, which are measured in the form of point clouds and the individual points of which are provided by the CAD program with polygons in the form of triangular surfaces of every three adjacent points. A smooth surface is generated from this combination of triangular surfaces by way of a surface-creation function. The process of averaging individual measured surface contours is carried out by a computer and it preferably includes the entire contact surface between the seat user and the seat.
In the third and last step, the average surface contour is expanded slightly in at least one direction in space, thus resulting in a “modified surface contour.” Taking the region of the depression created by the buttocks as an example, this means that the average surface contour is displaced at least in the transverse direction of the seat, that is, in the direction of the outer boundary line of the set of curves.
In the case of the production of a supporting shell, the displacement (“offset”) is calculated by the thickness of the pad that is applied to that side of the supporting shell that is oriented toward the seat user. The thickness of the pad usually varies over the extent of the seating surface and/or backrest. The offset is necessary to enable the “95% man” to find sufficient space within the contour of the depression created by the buttocks subsequently on the supporting shell without the space available becoming “too narrow” for the “95% man.” The pad on the supporting shell serves as a “comfort layer” and comprises a cushioning material, such as foam, as its essential component. The expansion of the average surface contour includes at least a considerable portion of the contact surface of the seat.
In the case of the production of a cushion support, the offset is dependent on different factors such as the foam hardness of the cushion support. Basically, the offset can also be dispensed with or it can turn out to be very small since the expansion of the average surface contour can already be achieved to a satisfactory extent by means of the resilience of the cushion support, if appropriate.
The expansion of the average surface contour shall not be understood to mean a uniform, linear “enlargement” of the average surface contour, but instead an offset in the direction of the upper percentile of all measured surface contours, it being possible for the offset along the seat to deviate more or less strongly from a linear and uniform enlargement. The extent of offset along the height and width of the measured surface contour is determined, for example, by an evaluator while allowing for anatomical and ergonomic criteria.
For example, the expansion at least in portions of the seat cushion and/or backrest can be carried out up to the extent of an “80% surface contour.” Since the largest surface contours originate from very large and/or very corpulent test subjects, for whom conventional seats are also too narrow, an expansion of the average surface contour that exceeds the “80% extent” would impair the seating comfort for shorter and/or thinner seat users since these seat users would then find insufficient (lateral) support on the seat cushion and/or the backrest.
In principle, a compression of the average surface contour can also take place, at least in portions.
Unlike a seat shell that is individually adapted to a single seat user as is the case in racing cars, for example, the process of the invention naturally implies a compromise since the measured surface contours are “blurred” and distorted. Nevertheless, the supporting shell or cushion support thus produced according to the invention by means of a superimposition of the measured surface contours onto each other forms a surprisingly well-fitting surface of contact for all possible seat users with the seating surface and/or the backrest in spite of the differences in height, weight and physique of the test subjects.
In the preferred case where the depression created by the buttocks is used as the selected common section of the contact surface, this good fit can be explained, inter alia, by the differences in the shapes of the male pelvis and the female pelvis. The supporting shell produced according to the invention provides the good fit described above since the female pelvis is broader in relation to the male pelvis and the width of the depression created by the buttocks of a female test subject is within a relatively narrow range in spite of the height and weight of women being lesser on average than that of men.
Likewise, the lower section of the back that is adjacent to the depression created by the buttocks of the test subjects is suitable for use as the selected region for the superimposition of the measured surface contours onto each other.
In this preferred embodiment of the process of the invention with reference to the region of the depression created by the buttocks of the test subjects or the lower region of the back, the central and, more particularly, the upper region of the back is displaced in the vertical axis of the seat in the case of the plurality of test subjects. In the case of the production of a supporting shell, this can be easily compensated for by way of a lesser contouring of the supporting shell in the back region in conjunction with a thicker pad (cushioning layer). In the case of the production of a cushion support, the thickness of the cushion support is increased slightly in the back region. In both cases, a conventional lumbar support within the meaning of a bubble that can be activated separately and that has a variable volume is usually dispensed with since the height of such a lumbar support would not be suitable for all possible seat users.
Furthermore, the invention differs fundamentally from seats that are known in the prior art and that include recesses in the seat cushion, which recesses receive so-called “vacuum cushions” comprising pourable bulk material, as described in DE 199 10 427 A1 or DE 695 05 131 T2, for example. Also, seats having pockets which are placed thereon and comprise foam cushions having open-celled, self-inflating cushioning foam (DE 10 2004 013 674 A1) and seats that have cushions comprising a loose filling material and/or a fluid that can be redistributed by applying a magnetic or electric field, by applying an electric current, by heating or by hydraulic excitation (DE 10 2006 032 891 A1) are far from the present invention.
In an advantageous embodiment of the invention, the supporting shell or the cushion support serve for producing a seat for a vehicle. Accordingly, the series of measurements is carried out with test subjects that sit down in a posture corresponding to the sitting posture in the vehicle, for which the seat is intended. As mentioned above, the test subjects, when seated, preferably carry out movements required for performing the task of driving or other movements typical of the operation of the vehicle.
The CAD data set of the supporting shell or the cushion support can be used in CAD programs when designing a vehicle seat.
Seats that are produced using a supporting shell produced according to the process of the invention can be provided with a very thin cushioning pad; yet they still offer very good seating comfort since the pad, due to the good fit of the supporting shell, is only required to compensate for small “deviations” in the shape of the supporting shell from the body form of the seat user. This results in less installation space and low weight of the seat.
In an advantageous embodiment of the invention, the pad is in the form of a fluid-tight jacket having a spacer structure disposed in the interior of the jacket. The spacer structure is composed of layers of fabric that extend parallel to each other and are joined together by spacer threads. The jacket includes a hose line or a connection for a hose line in order to be able to control the amount of fluid inside the jacket. Such a pad is described in co-pending application Ser. No. 13/186,240 (issued as U.S. Pat. No. 8,424,967) entitled “Cushion for a Seat and Method of Adapting Same,” filed on even date herewith, the disclosure of which is herein expressly incorporated by reference.
As is known from the prior art cited above, a delivery device can additionally be provided, by which a fluid can be introduced into the pad or removed from the pad entirely or in part. The fluid can be a liquid or a gaseous substance.
Preferably, an adjusting device is provided in a seat produced according to the process of the invention for altering the inclination of the backrest relative to the seating surface. The gap between the backrest and the seating surface is relatively small and is barely noticeable to a seat user due to the cushioning pad.
In another embodiment of the invention, the inclination of the backrest relative to the seating surface can be fixed so as to be unalterable by the use of an integrally formed supporting structure. This results in a transition that is free of gaps between the backrest and the seating surface, preferably in conjunction with a cushioning pad that likewise covers both regions of the seat without interruption.
Seats that are produced using a cushion support produced according to the process of the invention can be provided with a relatively very thin cushion support and they still offer very good seating comfort since the cushion support, due to its good fit, is only required to compensate for small “deviations” from the body form of the seat user. This results in less installation space and low weight of the seat. The supporting substructure comprising the seating surface and/or backrest of the seat can be planar as far as possible or it can have a three-dimensional contour. However, the use of a supporting shell produced according to the invention as a supporting substructure is ruled out since there would hardly be any free space in such a supporting shell for a contouring of the cushion support since the cushion support would have to be of approximately even thickness over its entire surface extent due to the contouring of the supporting shell.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.